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William R. Watt
 
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Default newbie buiding a catamaran

"Matthias Broersma" (matthias.broersmaATNOSPAMPLEASEfastwebnet.it) writes:
how thin (i hope it is like that it should be written) can plywood be found?


3-4 mm

and if i fave a rather complex shape, is it easy to 'bend' it?


numbers vary. I have some raduis of curvature numbers from John Stewart's
book on my website under "Boats" (see below) but I've seen different
numbers in another book. I've seen plywood standards websites mentioned in
this newsgroup. maybe if you email the manufacturer they will know the
bending raduis of what they make. you can also find at the same place on
my website formulae for calculating radius of curvature and a Basic
program for calculating beam camber which also displays the raduis of
curvature.

what should i use as coating for protection?


first seal all the edges well with resin such as polyester or epoxy to
keep water from getting into the end grain. what you do after that depends
on how long the boat will be in the water and on how long you want the
boat to last. for a boat that's only in the water for a few hours at a
time I make sure the edges are well sealed and then just paint. some
people also fibreglass the seams and then paint. other people fibreglass
all of the outside which will be under water and paint. some people
fibreglass the whole outside and paint. other people fibreglass both the
outside and the inside of the hull and paint.

thanks
and have a good evening.
matthias


there are also three kinds of plywood. the first kind "interior" made
without waterproof glue is usually not recommended unless you cover all
the plywood with fibreglass to keep it from ever getting wet. the second
kind "exterior" made with waterproof glue for house construction can last
10-15 years on a boat hull. the third kind "marine" made to a better
standard costs a lot more but can last 25 years on a boat hull. plywood
which has been completey sealed with a lot of fibreglass can last
indefinitely on a boat hull but that costs more and the boat will be
heavier than a boat without all the fibreglass on it.

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